583 lines
14 KiB
Groff
583 lines
14 KiB
Groff
.\"
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.\" $FreeBSD$
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.\"
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.\" $KAME$
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.\"
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.\" Copyright (C) 1998, 1999, 2000 and 2001 WIDE Project.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the project nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd March 13, 2000
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.Dt IP6FW 8
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.Os
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.Sh NAME
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.Nm ip6fw
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.Nd controlling utility for IPv6 firewall
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.Sh SYNOPSIS
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.Nm
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.Op Fl nq
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.Oo
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.Fl p Ar preproc
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.Oo Fl D
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.Ar macro Ns Op = Ns Ar value
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.Oc
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.Op Fl U Ar macro
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.Oc
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.Ar pathname
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.Nm
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.Op Fl n
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.Op Fl f | Fl q
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flush
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.Nm
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.Op Fl nq
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zero
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.Op Ar number ...
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.Nm
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.Op Fl n
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delete
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.Ar number ...
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.Nm
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.Op Fl aftN
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list
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.Op Ar number ...
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.Nm
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.Op Fl ftN
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show
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.Op Ar number ...
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.Nm
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.Op Fl nq
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add
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.Op Ar number
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.Ar action
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.Op log
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.Ar proto
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from
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.Ar src
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to
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.Ar dst
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.Op via Ar name | ipv6no
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.Op Ar options
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.Sh DESCRIPTION
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To ease configuration, rules can be put into a file which is
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processed using
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.Nm
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as shown in the first synopsis line.
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An absolute
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.Ar pathname
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must be used.
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The file
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will be read line by line and applied as arguments to the
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.Nm
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utility.
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.Pp
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Optionally, a preprocessor can be specified using
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.Fl p Ar preproc
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where
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.Ar pathname
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is to be piped through.
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Useful preprocessors include
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.Xr cpp 1
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and
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.Xr m4 1 .
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If
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.Ar preproc
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does not start with a slash
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.Pq Ql /
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as its first character, the usual
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.Ev PATH
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name search is performed.
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Care should be taken with this in environments where not all
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file systems are mounted (yet) by the time
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.Nm
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is being run (e.g.\& when they are mounted over NFS).
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Once
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.Fl p
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has been specified, optional
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.Fl D
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and
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.Fl U
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specifications can follow and will be passed on to the preprocessor.
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This allows for flexible configuration files (like conditionalizing
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them on the local hostname) and the use of macros to centralize
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frequently required arguments like IP addresses.
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.Pp
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The
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.Nm
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code works by going through the rule-list for each packet,
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until a match is found.
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All rules have two associated counters, a packet count and
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a byte count.
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These counters are updated when a packet matches the rule.
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.Pp
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The rules are ordered by a
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.Dq line-number
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from 1 to 65534 that is used
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to order and delete rules.
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Rules are tried in increasing order, and the
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first rule that matches a packet applies.
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Multiple rules may share the same number and apply in
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the order in which they were added.
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.Pp
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If a rule is added without a number, it is numbered 100 higher
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than the previous rule.
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If the highest defined rule number is
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greater than 65434, new rules are appended to the last rule.
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.Pp
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The delete operation deletes the first rule with number
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.Ar number ,
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if any.
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.Pp
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The list command prints out the current rule set.
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.Pp
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The show command is equivalent to `ip6fw -a list'.
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.Pp
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The zero operation zeroes the counters associated with rule number
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.Ar number .
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.Pp
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The flush operation removes all rules.
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.Pp
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Any command beginning with a
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.Sq # ,
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or being all blank, is ignored.
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.Pp
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One rule is always present:
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.Bd -literal -offset center
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65535 deny all from any to any
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.Ed
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.Pp
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This rule is the default policy, i.e., do not allow anything at all.
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Your job in setting up rules is to modify this policy to match your
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needs.
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.Pp
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The following options are available:
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.Bl -tag -width flag
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.It Fl a
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While listing, show counter values.
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See also
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.Dq show
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command.
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.It Fl f
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Do not ask for confirmation for commands that can cause problems if misused
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(ie; flush).
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.Ar Note ,
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if there is no tty associated with the process, this is implied.
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.It Fl n
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Only check syntax of the command strings,
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without actually passing them into the kernel.
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.It Fl q
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While adding, zeroing or flushing, be quiet about actions (implies '-f').
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This is useful for adjusting rules by executing multiple ip6fw commands in a
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script (e.g.\& sh /etc/rc.firewall), or by processing a file of many ip6fw rules,
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across a remote login session.
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If a flush is performed in normal
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(verbose) mode, it prints a message.
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Because all rules are flushed, the
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message cannot be delivered to the login session, the login session is
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closed and the remainder of the ruleset is not processed.
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Access to the
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console is required to recover.
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.It Fl t
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While listing, show last match timestamp.
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.It Fl N
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Try to resolve addresses and service names in output.
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.El
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.Pp
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.Ar action :
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.Bl -hang -offset flag -width 16n
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.It Ar allow
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Allow packets that match rule.
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The search terminates.
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Aliases are
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.Ar pass ,
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.Ar permit ,
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and
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.Ar accept .
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.It Ar deny
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Discard packets that match this rule.
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The search terminates.
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.Ar Drop
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is an alias for
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.Ar deny .
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.It Ar reject
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(Deprecated.)
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Discard packets that match this rule, and try to send an ICMPv6
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host unreachable notice.
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The search terminates.
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.It Ar unreach code
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Discard packets that match this rule, and try to send an ICMPv6
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unreachable notice with code
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.Ar code ,
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where
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.Ar code
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is a number from zero to 255, or one of these aliases:
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.Ar noroute ,
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.Ar admin ,
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.Ar notneighbor ,
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.Ar addr ,
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or
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.Ar noport ,
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The search terminates.
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.It Ar reset
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TCP packets only.
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|
Discard packets that match this rule,
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and try to send a TCP reset (RST) notice.
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The search terminates
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.It Ar count
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Update counters for all packets that match rule.
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The search continues with the next rule.
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.It Ar skipto number
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Skip all subsequent rules numbered less than
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.Ar number .
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The search continues with the first rule numbered
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.Ar number
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or higher.
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.El
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.Pp
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If the kernel was compiled with
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.Dv IPV6FIREWALL_VERBOSE ,
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|
then when a packet matches a rule with the
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.Dq log
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|
keyword or a clear/resetlog is performed, a message will be logged to
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|
.Xr syslogd 8 ,
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|
or, if that fails, to the console.
|
|
If the kernel was compiled with the
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.Dv IPV6FIREWALL_VERBOSE_LIMIT
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|
option, then logging will cease after the number of packets
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|
specified by the option are received for that particular
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chain entry.
|
|
When this limit is reached, the limit and rule number will be logged.
|
|
Logging may then be re-enabled by clearing
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|
the packet counter for that entry.
|
|
.Pp
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|
The
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|
.Xr syslogd 8
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|
logging and the default log limit are adjustable dynamically through the
|
|
.Xr sysctl 8
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|
interface.
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|
.Pp
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.Ar proto :
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|
.Bl -hang -offset flag -width 16n
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|
.It Ar ipv6
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|
All packets match.
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|
The alias
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|
.Ar all
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|
has the same effect.
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|
.It Ar tcp
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Only TCP packets match.
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.It Ar udp
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Only UDP packets match.
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|
.It Ar ipv6-icmp
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|
Only ICMPv6 packets match.
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.It Ar <number|name>
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Only packets for the specified protocol matches (see
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.Pa /etc/protocols
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|
for a complete list).
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|
.El
|
|
.Pp
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|
.Ar src
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|
and
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.Ar dst :
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|
.Bl -hang -offset flag
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.It Ar <address/prefixlen>
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.Op Ar ports
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.El
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.Pp
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The
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.Em <address/prefixlen>
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|
may be specified as:
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.Bl -hang -offset flag -width 16n
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.It Ar ipv6no
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An ipv6number of the form
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.Li fec0::1:2:3:4 .
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.It Ar ipv6no/prefixlen
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|
An ipv6number with a prefix length of the form
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.Li fec0::1:2:3:4/112 .
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.El
|
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.Pp
|
|
The sense of the match can be inverted by preceding an address with the
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.Dq not
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modifier, causing all other addresses to be matched instead.
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This
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does not affect the selection of port numbers.
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.Pp
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With the TCP and UDP protocols, optional
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.Em ports
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may be specified as:
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.Pp
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.Bl -hang -offset flag
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.It Ns {port|port-port} Ns Op ,port Ns Op ,...
|
|
.El
|
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.Pp
|
|
Service names (from
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.Pa /etc/services )
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|
may be used instead of numeric port values.
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|
A range may only be specified as the first value,
|
|
and the length of the port list is limited to
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|
.Dv IPV6_FW_MAX_PORTS
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(as defined in
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.In netinet6/ip6_fw.h )
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|
ports.
|
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.Pp
|
|
Fragmented packets which have a non-zero offset (i.e., not the first
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fragment) will never match a rule which has one or more port
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specifications.
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See the
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.Ar frag
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|
option for details on matching fragmented packets.
|
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.Pp
|
|
Rules can apply to packets when they are incoming, or outgoing, or both.
|
|
The
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.Ar in
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keyword indicates the rule should only match incoming packets.
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The
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.Ar out
|
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keyword indicates the rule should only match outgoing packets.
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.Pp
|
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To match packets going through a certain interface, specify
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the interface using
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.Ar via :
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.Bl -hang -offset flag -width 16n
|
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.It Ar via ifX
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Packet must be going through interface
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.Ar ifX .
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.It Ar via if*
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Packet must be going through interface
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.Ar ifX ,
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where X is any unit number.
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.It Ar via any
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Packet must be going through
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.Em some
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interface.
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.It Ar via ipv6no
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Packet must be going through the interface having IPv6 address
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.Ar ipv6no .
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.El
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.Pp
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The
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.Ar via
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keyword causes the interface to always be checked.
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If
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.Ar recv
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or
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.Ar xmit
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is used instead of
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.Ar via ,
|
|
then the only receive or transmit interface (respectively) is checked.
|
|
By specifying both, it is possible to match packets based on both receive
|
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and transmit interface, e.g.:
|
|
.Pp
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.Dl "ip6fw add 100 deny ip from any to any out recv ed0 xmit ed1"
|
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.Pp
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The
|
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.Ar recv
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interface can be tested on either incoming or outgoing packets, while the
|
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.Ar xmit
|
|
interface can only be tested on outgoing packets.
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So
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.Ar out
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is required (and
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.Ar in
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invalid) whenever
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.Ar xmit
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is used.
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Specifying
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.Ar via
|
|
together with
|
|
.Ar xmit
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or
|
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.Ar recv
|
|
is invalid.
|
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.Pp
|
|
A packet may not have a receive or transmit interface: packets originating
|
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from the local host have no receive interface, while packets destined for
|
|
the local host have no transmit interface.
|
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.Pp
|
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Additional
|
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.Ar options :
|
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.Bl -hang -offset flag -width 16n
|
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.It frag
|
|
Matches if the packet is a fragment and this is not the first fragment
|
|
of the datagram.
|
|
.Ar frag
|
|
may not be used in conjunction with either
|
|
.Ar tcpflags
|
|
or TCP/UDP port specifications.
|
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.It in
|
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Matches if this packet was on the way in.
|
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.It out
|
|
Matches if this packet was on the way out.
|
|
.It ipv6options Ar spec
|
|
Matches if the IPv6 header contains the comma separated list of
|
|
options specified in
|
|
.Ar spec .
|
|
The supported IPv6 options are:
|
|
.Ar hopopt
|
|
(hop-by-hop options header),
|
|
.Ar route
|
|
(routing header),
|
|
.Ar frag
|
|
(fragment header),
|
|
.Ar esp
|
|
(encapsulating security payload),
|
|
.Ar ah
|
|
(authentication header),
|
|
.Ar nonxt
|
|
(no next header), and
|
|
.Ar opts
|
|
(destination options header).
|
|
The absence of a particular option may be denoted
|
|
with a
|
|
.Dq \&!
|
|
.Em ( "not working yet" ) .
|
|
.It established
|
|
Matches packets that have the RST or ACK bits set.
|
|
TCP packets only.
|
|
.It setup
|
|
Matches packets that have the SYN bit set but no ACK bit.
|
|
TCP packets only.
|
|
.It tcpflags Ar spec
|
|
Matches if the TCP header contains the comma separated list of
|
|
flags specified in
|
|
.Ar spec .
|
|
The supported TCP flags are:
|
|
.Ar fin ,
|
|
.Ar syn ,
|
|
.Ar rst ,
|
|
.Ar psh ,
|
|
.Ar ack ,
|
|
and
|
|
.Ar urg .
|
|
The absence of a particular flag may be denoted
|
|
with a
|
|
.Dq \&! .
|
|
A rule which contains a
|
|
.Ar tcpflags
|
|
specification can never match a fragmented packet which has
|
|
a non-zero offset.
|
|
See the
|
|
.Ar frag
|
|
option for details on matching fragmented packets.
|
|
.It icmptypes Ar types
|
|
Matches if the ICMPv6 type is in the list
|
|
.Ar types .
|
|
The list may be specified as any combination of ranges
|
|
or individual types separated by commas.
|
|
.El
|
|
.Sh CHECKLIST
|
|
Here are some important points to consider when designing your
|
|
rules:
|
|
.Bl -bullet -offset flag
|
|
.It
|
|
Remember that you filter both packets going in and out.
|
|
Most connections need packets going in both directions.
|
|
.It
|
|
Remember to test very carefully.
|
|
It is a good idea to be near the console when doing this.
|
|
.It
|
|
Do not forget the loopback interface.
|
|
.El
|
|
.Sh FINE POINTS
|
|
There is one kind of packet that the firewall will always discard,
|
|
that is an IPv6 fragment with a fragment offset of one.
|
|
This is a valid packet, but it only has one use, to try to circumvent
|
|
firewalls.
|
|
.Pp
|
|
If you are logged in over a network, loading the KLD version of
|
|
.Nm
|
|
is probably not as straightforward as you would think
|
|
.Em ( "not supported" ) .
|
|
I recommend this command line:
|
|
.Bd -literal -offset center
|
|
kldload ip6fw && \e
|
|
ip6fw add 32000 allow all from any to any
|
|
.Ed
|
|
.Pp
|
|
Along the same lines, doing an
|
|
.Bd -literal -offset center
|
|
ip6fw flush
|
|
.Ed
|
|
.Pp
|
|
in similar surroundings is also a bad idea.
|
|
.Sh PACKET DIVERSION
|
|
not supported.
|
|
.Sh EXAMPLES
|
|
This command adds an entry which denies all tcp packets from
|
|
.Em hacker.evil.org
|
|
to the telnet port of
|
|
.Em wolf.tambov.su
|
|
from being forwarded by the host:
|
|
.Pp
|
|
.Dl ip6fw add deny tcp from hacker.evil.org to wolf.tambov.su 23
|
|
.Pp
|
|
This one disallows any connection from the entire hackers network to
|
|
my host:
|
|
.Pp
|
|
.Dl ip6fw add deny all from fec0::123:45:67:0/112 to my.host.org
|
|
.Pp
|
|
Here is a good usage of the list command to see accounting records
|
|
and timestamp information:
|
|
.Pp
|
|
.Dl ip6fw -at l
|
|
.Pp
|
|
or in short form without timestamps:
|
|
.Pp
|
|
.Dl ip6fw -a l
|
|
.Sh SEE ALSO
|
|
.Xr ip 4 ,
|
|
.Xr ipfirewall 4 ,
|
|
.Xr protocols 5 ,
|
|
.Xr services 5 ,
|
|
.Xr reboot 8 ,
|
|
.Xr sysctl 8 ,
|
|
.Xr syslogd 8
|
|
.Sh HISTORY
|
|
A
|
|
.Nm
|
|
utility first appeared in
|
|
.Fx 4.0 .
|
|
.Sh AUTHORS
|
|
.An Ugen J. S. Antsilevich ,
|
|
.An Poul-Henning Kamp ,
|
|
.An Alex Nash ,
|
|
.An Archie Cobbs .
|
|
.Pp
|
|
.An -nosplit
|
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API based upon code written by
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.An Daniel Boulet
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for BSDI.
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.Sh BUGS
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.Em WARNING!!WARNING!!WARNING!!WARNING!!WARNING!!WARNING!!WARNING!!
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.Pp
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This program can put your computer in rather unusable state.
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When
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using it for the first time, work on the console of the computer, and
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do
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.Em NOT
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do anything you do not understand.
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.Pp
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When manipulating/adding chain entries, service and protocol names are
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not accepted.
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